1. Field of the Invention
The present invention relates to vehicles, and, more particularly, to vehicles which are controlled using a guidance control system.
2. Description of the Related Art
Vehicle leader-follower systems are used in various military and transportation applications in which one vehicle, called the “leader”, moves along the ground, in the air, or through space, and one or more other vehicles, each called a “follower”, follow the leader and/or move along a path that is displaced from the path taken by the leader.
A leader-follower system approach can have constraints in which the follower is too slow to adequately respond to changes in speed and bearing of the leader. The follower must first observe or be communicated the change in speed and bearing of the leader before providing inputs to its controls to adjust its own trajectory in order to stay at the proper offset distance from the leader. Thus, there is an inherent delay between the leader changing its speed and/or bearing and the follower changing its speed and/or bearing. This inherent delay causes poor performance in maintaining the same path as the leader and the proper follow distance unless the follow distance is great enough to allow for the sensing and communications delay time.
In some applications autonomous vehicle convoys, utilize a common route planning among vehicles in the convoy for maintaining a formation among the vehicles of the convoy. The convoy consists of a leader vehicle and follower vehicles which receive a guidance signal from the vehicle ahead of it for maintaining a path of travel. Such systems may utilize a sensing system to maintain a safe distance with the vehicle ahead. Each member vehicle of the convoy knows the route and destination in advance, and the location along the route at any given point in time.
Vehicles, such as those used in the agricultural, forestry and construction industries are typically controlled by an operator sitting at an operator station. However, it is also becoming more common for such vehicles to be controlled automatically through the use of a vehicle guidance system. Often an operator remains at the operator station so that control of the vehicle can be overtaken manually should the need arise. The operator typically drives the work vehicle to a predefined area, such as an agricultural field, then actuates the guidance system so that the work vehicle can be automatically driven in a predefined path through the field. The operator also manually attaches any tools (e.g., implements), and loads any application materials (such as fertilizer, herbicides, etc.). Regardless of the application, the operator is always present and ultimately under final (over-ride) control of the work vehicle.
For semi-autonomous systems, it is also known to provide various geospatial data to the controller onboard the vehicle such that the position of the vehicle within a geospatial framework can be determined within certain tolerances. For example, in the case of an agricultural sprayer, it is known to utilize global positioning system (GPS) data to turn on and off different sprayer boom sections as the sprayer traverses across a field.
The future outlook for off-highway agricultural and construction equipment shows an increased use of automated and unmanned technologies to increase the efficiency of operations with these vehicles. Some off-highway agricultural and construction activities demand precise and reliable vehicle control of one vehicle to a fixed offset from and close proximity to a second vehicle. Human operators with the necessary skill set are costly and sometimes unfeasible. Fatigue and stress in humans also contribute to human error which can result in costly equipment repairs and down time.
What is needed in the art is a control system that allows precise, reliable, and repeatable vehicle control beyond the skills of a human operator.